Foil lamination is gaining popularity as a method for applying decorative surfaces to a variety of substrates, particularly substantially flat, contoured panels used as kitchen cabinet doors.
Foils used in foil lamination typically comprise thin sheets of plastic which are highly flexible and able to stretch when heated. Commercially available foils typically comprise thin sheets of plastic material, such as polyethylene, polypropylene, polyvinyl chloride (PVC) and polyester from about 0.2 to about 4.0 mm in thickness, more preferably about 0.3 mm to about 1.0 mm., with one side of the foil being provided with a decorative finish. Plastic foils are available in a variety of finishes, for example wood grain, stones such as marble, suede, etc. These foils are suitable for both indoor and outdoor use, being weatherproof, virtually maintenance free and very easy to clean.
Suitable films are available from C. I. Kasei Co., Ltd. under the trademark BONLEX. Bonlex material is a thermoplastic, thermo-formable PVC material specially designed for membrane press applications. It consists of a combination of polyvinyl chloride and other synthetic materials.
The foil's flexible properties allow it to conform to the surface contours of a substrate and provide a continuous layer of material over the substrate, the foil "stretching into" depressions such as grooves, channels, holes etc. in the surface. These depressions are generally of a decorative nature, for example grooves cut into the face of a cabinet door.
Foil lamination is typically accomplished by adhering a thin plastic foil onto a substrate under pressure in a membrane form press. The substrate onto which the foil is adhered typically comprises a rigid, inexpensive material which can be easily cut, routed, milled or sanded into a variety of shapes and contours, for example fibreboard. One preferred substrate for foil lamination is medium density fibreboard.
The foil is adhered to the substrate by a thin layer of glue applied between the foil and the substrate. The glue may be applied to one or both of the substrate and the foil. Typically, the back of the foil is provided with an adhesive primer which improves adhesion of the foil to the substrate. The glue is typically either water or solvent based and may be heat activated. Heat activated glues require the application of heat in the membrane form press.
The membrane form press typically comprises a pressure chamber into which the foil-covered substrate is loaded, with the lower surface, i.e. the surface of the substrate which is not to be laminated, typically lying flat on a platform in the pressure chamber.
Pressure is generated in the pressure chamber by, for example, compressed air. The pressure forces the foil into intimate contact with the substrate such that a strong bond is formed between the foil and the substrate and the foil closely follows the contours of the substrate.
Thus, in one simple operation in a membrane form press, a substrate may be quickly laminated with a continuous sheet of foil. Conventional membrane presses are known to laminate foil onto the upper surface and the sides of a flat panel. Suitable membrane form presses are manufactured by Friz Maschinenbau GmbH of Weinsberg, Germany which provide controlled glue applications, even heating of the foil, hydraulic and pneumatic presses and optional bottom vacuum systems.
Typically, the foil sheet applied to the substrate has a larger surface area than the surface area of the substrate to be covered. Also, the foil tends to stretch during the pressing process. This results in excess foil extending from the laminated surface after the lamination process. This excess foil must be trimmed from the edges of the substrate, the trimming frequently being done manually with a cutting instrument such as a knife.
For many applications, lamination with foil is preferred over lamination with other conventional high pressure laminates, such as Arborite.TM. sheeting. Arborite sheeting is a moderately flexible material made from decorative papers laminated at high pressure with thermosetting melamine resin, which is typically applied to a substrate by glue, and is commonly used as a surface for countertops and tabletops.
Conventional laminates such as Arborite sheeting have limited flexibility and are only practically able to bend in one dimension around smoothly rounded corners having a relatively large radius of curvature. This limits the applicability of conventional laminates.
In a surface such as a tabletop having both an upper and side surface, it is typically not practically possible to laminate the entire upper and side surfaces with a single sheet of Arborite sheeting or like materials due to their ability to bend in only one dimension. In a tabletop having a rectangular upper surface and a side surface comprising four sides, for example, it is typical to laminate the upper surface and two of the sides with a first continuous sheet of conventional laminate and to laminate the remaining two sides with separate pieces of laminate.
The joints formed between adjoining sheets of laminate are both aesthetically unpleasing and difficult to clean. The collection of dirt in such joints is of concern from a health standpoint, particularly in surfaces which should be sanitized, such as tabletops and countertops.
Further, the separate application of numerous pieces of laminate to a substrate, including time spent cutting each piece of laminate to the correct size and clamping it to the substrate, results in a substantial time cost. Some substrates have such intricate contours formed in their surfaces that it is not only inconvenient, but impossible, to laminate such substrates with a conventional laminate. For example, it is usually difficult or impossible to laminate the surface of a substrate having recesses with a continuous sheet of conventional laminates such as Arborite sheeting. These recesses typically cannot be laminated with one piece of conventional sheeting since they require bending of the laminate in more than one dimension. Also, the radii of the curves in these recesses are frequently too small to be closely followed by conventional sheeting with limited flexibility.
Lamination with highly flexible foils overcomes many of the problems encountered with conventional laminates, since foils are not limited to bending in one dimension and can stretch about relatively sharp corners and rounded corners having a relatively small radius of curvature. Further, foils are capable of very closely following the contours of a substrate, even very intricate decorative or functional recesses carved into a surface. Thus, with foil lamination it is possible to provide a continuous sheet of material over the surface of a substrate, even substrates with relatively intricate recesses. Lamination with a continuous sheet of flexible foil results in a surface which is both more aesthetically pleasing and easier to clean than a conventionally laminated surface having joints.
Cabinet doors and tabletops are known which are foil laminated with a continuous sheet of material on both their upper and side surfaces. Such cabinet doors and tabletops have an upper surface and a side surface extending downward from the upper surface about the perimeter of the upper surface, with the side surface and lower surface meeting at a right angled lower edge and with the foil applied abruptly terminating at this lower edge where the side surface and the lower surface intersect. While the abrupt termination of the foil at the lower edge may be acceptable in some applications where the lower edge of the laminated substrate is not normally noticeable, such as in cabinet doors, abrupt termination at the lower edge of a tabletop has been appreciated by the present inventor as not preferred.